Polymers that contain α,β-unsaturated carboxylic acids with polyoxyalkylene side chains have been used in concrete technology as dispersing agents, for example, as plasticizers. The addition of such polymers to cements allows to reduce the water content, which can be desirable for the processing and stability of the concrete. These polymers have a comb polymer structure. There is a series of such comb polymers which, besides ester and carboxylic acid groups, also have amide groups. Two processes can be used for producing generic comb polymers. In one process, such comb polymers are prepared from unsaturated carboxylic acid, ester, ether, amide, and/or imide-functional monomers by free-radical polymerizations. In another process, the polymers are prepared in a so-called polymer-analogous reaction from a polycarboxylic acid comprising at least one acrylic acid unit or at least one methacrylic acid unit and the respective alcohols and/or amines. In this process, the comb polymer is obtained by an esterification and/or amidation of the polycarboxylic acid or a salt or an anhydride thereof.
Despite the improvement regarding plastification, it can still be a challenge to adapt to the various processing conditions globally used in the manufacturing of concrete. This is due to the various types of local climate, cements, aggregates, cement replacement fillers, etc., and the broad field of use, such as ready-mix concrete, air-placed concrete, self-compacting concrete or concrete mixed on site. Therefore, it can be beneficial to provide special additives meeting completely different specifications.
It can be beneficial to provide new additives which can be used as dispersants, for example, as plasticizers for hydraulically setting systems and, for example, for new fields of use.
In comparative plasticizers based on comb polymers, the processing is good in the beginning due to the very strong water reduction. However, this subsequently quickly deteriorates, which results in poor processing of the hydraulically setting composition within a short time.